Vacuum cleaners are generally supplied with a range of tools for dealing with specific types of cleaning. The tools include a floor tool for general on-the-floor cleaning. Efforts have been made to improve the pick up performance of floor tools on carpeted floors. Some tools have a brush mounted in the suction inlet which is rotated so as to agitate the floor surface in the same manner as the brush bar of an upright vacuum cleaner. The brush can be rotated by the use of an air turbine or by an electric motor which is powered by a power supply derived from the main body of the cleaner. However, this type of tool is typically more expensive than the passive floor tool and consumes power.
Efforts have also been made to improve floor tools in a more passive manner. For example, EP 1 320 317 discloses a floor tool having a suction channel bounded on at least one side by a working edge for engaging with and agitating the floor surface. Lint pickers on the underside of the tool act as a one-way gate, allowing hair, fluff and other fibrous material to pass under the lint picker when the floor tool is pushed along the floor, but to block the lint when the floor tool is pulled backwards. The repeated forward and backwards action of the floor tool across the floor surface traps the lint and rolls it into a ball such that it can be sucked by the floor tool. The floor tool also comprises a skirt of flexible bristles which surrounds, but is not part of, the underside of the floor tool. The skirt is movable between a deployed position, for use with cleaning hard floors, in which the skirt rides along the hard floor surface and serves to space the working edge from the floor surface, and a retracted position, for use when cleaning carpets, where the working edge is able to contact the floor surface and the skirt is retracted sufficiently not to impede movement of the floor tool across the carpeted surface.
It is known to provide a system for moving a bristle arrangement automatically between a retracted position and a deployed position depending on the nature of a floor surface to be cleaned. For example, GB 1,289,381 describes a floor tool having a pressure chamber delimited by a diaphragm fitted with bristles. The pressure chamber comprises springs which, when the pressure chamber is at atmospheric pressure, urge the diaphragm downwardly to move the bristles to the deployed position. The pressure chamber is connectable to an air flow passing through the floor tool, and thus a reduced pressure, by a valve located within the main body. The valve is connected by a push rod to a cup which has a lower surface arranged to face the floor surface.
When the floor tool is located on a hard floor surface, the lower surface of the cup is spaced from the floor surface by wheels located on the main body of the floor tool. The valve is maintained in a position in which the pressure chamber is isolated from the air flow passing through the floor tool, and so maintained at atmospheric pressure so that the springs urge the bristles to their deployed position. However, when the floor tool is located on a carpeted floor surface the wheels sink between the fibers of the floor surface so that the cup is brought into contact with the floor surface. The cup is pushed upwardly by the floor surface, which causes the valve to move to connect the pressure chamber to the air flow passing through the floor tool. The pressure within the pressure chamber is reduced, which causes the volume of the pressure chamber to decrease, against the biasing force of the springs, to move the bristles to their retracted position.